“I would remind you, brothers, of the gospel.”
1 Corinthians 15:1-7 NKJV
Moreover, brethren, I declare to you the gospel which I preached to you, which also you received and in which you stand,  by which also you are saved, if you hold fast that word which I preached to you-unless you believed in vain.  For I delivered to you first of all that which I also received: that Christ died for our sins according to the Scriptures,  and that He was buried, and that He rose again the third day according to the Scriptures,  and that He was seen by Cephas, then by the twelve.  After that He was seen by over five hundred brethren at once, of whom the greater part remain to the present, but some have fallen asleep.  After that He was seen by James, then by all the apostles.
To preach the Gospel to yourself means that you continually face up to your own sinfulness and then flee to Jesus through faith in his shed blood and righteous life.
It means that you appropriate, again by faith, the fact that Jesus fully satisfied the law of God. In both its precepts and penalty, he fulfilled the law of God in its most exacting requirements.
And he did this in our place as our representative and our substitute.
He is your propitiation, so that God’s holy wrath is no longer directed toward you.
To preach the Gospel to yourself means that you take at face value the precious words of
“Blessed are those whose lawless deeds are forgiven, and whose sins are covered; blessed is the man against whom the Lord will not count his sin.”
You believe on the testimony of God:
“There is therefore now no condemnation for those who are in Christ Jesus” (Romans 8:1).
You believe that “Christ redeemed us from the curse of the law by becoming a curse for us” (Galatians 3:13).
You believe he forgave you all your sins (Colossians 2:13), that he reconciled you “to present you holy and blameless and above reproach before him”
To preach the Gospel to yourself means you appropriate by faith the words of Isaiah 53:6:
“The Lord has laid on him the iniquity of us all.”
It means you dwell upon the promise that God has removed your transgressions from you as far as the east is from the west (Psalm 103:12), that he has blotted out your transgressions and remembers your sin no more (Isaiah 43:25).
(Excerpt taken from The Discipline of Grace)
Matthew 24:14 KJV
And this gospel of the kingdom shall be preached in all the world for a witness unto all nations; and then shall the end come.